Infant sleep quality is increasingly regarded as an important factor for children long-term functioning and adaptation. The early roots of sleep disturbances are still poorly understood and likely involve a complex interplay between prenatal and postnatal factors. This study investigated whether exclusive breastfeeding during the first 6 months moderated the association between maternal prenatal pandemic-related stress (PRS) and sleep problems in 24-months children born during the COVID-19 pandemic. We also explored the potential contribution of maternal postnatal anxiety in these relations. Seventy-eight infants (50% males) and their mothers provided complete data from birth to 24 months. Between 12 and 48 h from birth, maternal PRS during pregnancy was retrospectively reported as well as maternal anxiety and exclusive breastfeeding. Maternal anxiety and exclusive breastfeeding were also reported at 3 and 6 months after childbirth. Children sleep disturbances were reported at 24 months. Bayesian analyses revealed that maternal PRS was positively associated with sleep problems in children who were not exclusively breastfed from birth to 6 months. Findings add to the growing literature on the lasting impact of early pre- and postnatal experiences on child well-being and development.

This editorial summarises the clinical relevance of ‘chronopsychiatry’, defined as the interface between circadian science and mental health science. Chronopsychiatry represents a move towards time-variable perspectives on neurobiology and symptoms, with a greater emphasis on chronotherapeutic interventions.

I would like to thank Professor Ekirch for his reflections on ‘Have we lost sleep?’, which contain several points that I have already responded to within the paper following his peer review of my original submission to Medical History in 2023 (Professor Ekirch having voluntarily identified himself as a reviewer in a normally double-blind process). I acknowledge that the focus of my paper was on Ekirch’s original work from 2001; if I did not engage as he would have wished with his subsequent publications, this was simply because I do not perceive the same substantial developments in his thinking and research on the subject that he does. Indeed, the present critique by Ekirch amounts essentially to more of the same: a long list of references and quotes but little detailed discussion of any individual source. As my paper demonstrates, seemingly unambiguous evidence from a brief quotation can become less clear-cut when placed in context. I am sorry if I deploy the word ‘might’ more than Ekirch would like. This reflects, I hope, a healthy degree of uncertainty and intellectual humility in my approach to the complex issue of pre-industrial sleep. To extend Ekirch’s metaphor, if the jigsaw puzzle that both he and I are trying to assemble can take the form of a cat or a dog, it is possible that its true form is neither animal. The extent to which people woke in the night in pre-industrial Europe, the duration of such awakening, and the predominant cultural attitude towards this—concern, acceptance, or indifference—are topics about which it would seem wise to avoid sweeping statements and generalisations, given the relatively long period covered and the social, cultural, and individual diversity that must be taken into consideration. I can only repeat that I think amassing more brief references, and selectively citing relatively small physiological studies and anthropological evidence from global settings, is unlikely to provide much clarity, let alone definitive answers. I welcome Professor Ekirch’s contribution to this discussion as an indication that the question of segmented sleep in early modern Europe is by no means settled but is a matter of ongoing debate.

The objective was to examine associations between social jetlag and diet quality among young adults in the US using nationally representative data from the 2017–2018 NHANES survey, and evaluate effect modification by gender and race/ethnicity. Social jetlag was considered ≥2-hour difference in sleep midpoint (median of bedtime and wake time) between weekends and weekdays. Diet quality was assessed with the Healthy Eating Index (HEI)-2015 and its 13 dietary components. Ordinal logistic models were run with diet scores binned into tertiles as the outcome. Models accounted for potential confounders and survey weights. Effect modification by gender and race/ethnicity was examined. The study sample included 1,356 adults aged 20–39 years. 31% of young adults had social jetlag. Overall, there were no associations between social jetlag and diet quality. However, interaction analysis revealed several associations were race-specific (P, interaction<0.05). Among Black adults, social jetlag was associated with lower overall diet quality (OR = 0.4, 95% CI 0.2, 0.8; i.e. less likely to be in higher diet quality tertiles) and more unfavourable scores on Total Vegetables (OR = 0.6, 95% CI 0.3, 1.0) and Added Sugar (i.e. OR = 0.6, 95% CI 0.4, 0.9). For Hispanic adults, social jetlag was associated with worse scores for Sodium (OR = 0.6, 95% CI 0.4, 0.9) However, White adults with social jetlag had better scores of Greens and Beans (OR = 1.9, 95% CI 1.1, 3.2). Within a nationally representative sample of US young adults, social jetlag was related to certain indicators of lower diet quality among Black and Hispanic Americans.

The association of post-adoption experiences of discrimination with depressive symptoms was examined in 93 previously institutionalized (PI) youth (84% transracially adopted). Additionally, we explored whether sleep quality statistically moderated this association. Notably, we examined these associations after covarying a measure of autonomic balance (high/low frequency ratio in heart rate variability) affected by early institutional deprivation and a known risk factor for depression. PI youth exhibited more depressive symptoms and experiences of discrimination than 95 comparison youth (non-adopted, NA) raised in their biological families in the United States. In the final regression model, there was a significant interaction between sleep quality and discrimination, such that at higher levels of sleep quality, the association between discrimination and depression symptoms was non-significant. Despite being cross-sectional, the results suggest that the risk of depression in PI youth involves post-adoption experiences that appear unrelated to the impacts of early deprivation on neurobiological processes associated with depression risk. It may be crucial to examine methods of improving sleep quality and socializing PI youth to cope with discrimination as protection against discrimination and microaggressions.

Associations between obesity and mental illness have been identified, but they are complex and bidirectional(1). Weight loss interventions have been proposed as a potential strategy to improve mental health in individuals with overweight or obesity, but the evidence remains inconclusive(2). Additionally, the role of specific foods in a weight loss diet and mental health outcomes is not well understood(3). This study aimed to explore the association between weight loss (with and without almonds) and self-administered psychological and sleep assessments, including the Profile of Mood States (POMS), the Perceived Stress Scale (PSS), the Zung Self-Rating Depression Scale (ZSDS), and the Pittsburgh Sleep Quality Index (PSQI). Participants (n = 140, 47.5 ± 10.8 years) with overweight or obesity (BMI: 30.7 ± 2.3 kg/m2) were randomised to an energy-controlled almond-enriched diet (AED) or nut-free diet (NFD). Psychological and sleep assessments were conducted at baseline, after 3 months of weight loss, and after 6 months of weight maintenance. Data were analysed using mixed-effects models and linear regression. For POMS, total mood disturbance score (TMDS) (60.2%, p = 0.01), fatigue-inertia (21.2%, p = 0.003), and vigor-activity (19.9%, p<0.001) improved over time (with no different between groups), with improvements associated with the magnitude of weight loss (TMDS: β = 0.059, p = 0.02; fatigue-inertia: β = 0.268, p = 0.016; vigor-activity: β=-0.194, p = 0.048). No significant changes were observed in tension-anxiety, depression-dejection, anger-hostility, or confusion-bewilderment. A significant group x time interaction (p = 0.048) was found for the PSS, which increased in the NFD group (10.1%) and decreased in the AED (1%) during the weight maintenance phase. No significant changes were observed for the ZSDS. The PSQI demonstrated significant improvement in both groups over time for sleep quality (11.3%, p<0.001), sleep latency (24.3%, p<0.001), sleep disturbance (39.2%, p = 0.04), and daytime dysfunction (290.4%, p<0.001), but not for sleep duration or habitual sleep efficiency. Summed scores, generating the global sleep score (GSS), demonstrated an overall significant improvement in both groups over time (33.5%, p<0.001), and these improvements were associated with weight loss (GSS: β = 0.863, p<0.001). The findings emphasise the importance of evaluating mental health outcomes in weight loss interventions and highlight the potential influence of weight management on mood and sleep quality. Further research is warranted to explore the impact of diet composition on perceived stress and other mental health outcomes.

The classification of internet gaming disorder (IGD) as a mental condition for further study in 2013 marked the emerging recognition of potential mental health issues associated with internet and gaming addiction. The COVID-19 pandemic and the rapid growth of gaming technology have combined to increase internet gaming, resulting in unhealthy lifestyle behaviors, poor sleep quality and psychological distress. Identifying the complex interplay between internet problem use, sleep disorders and psychological distress is crucial. However, it remains unclear how physical activity and self-compassion could improve sleep quality when individuals experience IGD symptoms. The current study, therefore, examined the relationships between IGD, sleep quality, self-compassion, physical activity and psychological distress using a path analysis approach. The study, targeting young adults (N = 283), found that physical activity played a significant role in connecting the variables and supporting the overall fit of the model. The results suggest that interventions targeting individuals with IGD should focus on promoting physical activity participation and developing self-compassion. Future research should continue to investigate the effectiveness of clinical interventions that incorporate self-compassion and physical activity counseling for individuals with IGD.

Evidence suggests bidirectional relations between stress, sleep, and depressive symptoms in adolescence and young adulthood. Less research has disaggregated within- and between-person variance in these associations over time or within Latino/a college students. This study examined longitudinal, within-person reciprocal relations between stress, sleep, and depressive symptoms among 181 Latino/a adolescents (Mage = 18.10; SD = 0.41, 35% male) transitioning to college. Participants were assessed in their senior year of high school and annually until their fourth year of college. A random intercept cross-lagged panel model (RI-CLPM) was used to parse out within- and between-person sources of variance. Results indicated overall (between-person) relations among depressive symptoms and school/college stress and sleep problems. There were reciprocal within-person links between stress and sleep problems across the first two years of college. Within-person increases in depressive symptoms during the second year of college predicted more stress than usual in the third year, which predicted increased depressive symptoms in the fourth year. More sleep problems than usual in the third year of college predicted higher stress in the fourth year. Findings provide evidence for within-person cross-lagged relations among various domains of adjustment during college and may inform future prevention efforts for incoming Latino/a college students targeting mental health and sleep problems.

In natural settings, newborn calves hide for several days before joining the herd. It is unclear whether dairy calves housed indoors would show similar hiding behaviour. This study aimed to describe the use of an artificial hide provided to calves during temporary separation from the dam and assess the effect it has on lying and sleep-like behaviour, as well as heart rate variability (HRV). Twenty-eight cow-calf pairs were randomly assigned to having a hide (n = 14), or no hide (n = 14). Hide use (n = 14), as well as lying and sleep-like behaviour (n = 28), were recorded continuously via video camera during the first hour after the dam was removed for morning milking on day three to seven. Heart rate and R-R intervals were recorded using Polar equine monitors for a subsample of 12 calves (n = 6 per treatment) on day six. Descriptive statistics were calculated for hide use. Wilcoxon Signed Rank tests were used to evaluate whether having a hide affected lying and sleep-like behaviours as well as HRV. Hide use decreased over days and was highly variable between calves. Lying behaviour did not differ between treatments. Duration of sleep-like behaviour was higher for calves without a hide compared to those with a hide. Calves with a hide tended to show signs of higher HRV and parasympathetic activity compared to calves without a hide. Results suggest that providing a hiding space to young calves may be beneficial during periods when the cow is removed from the pen for milking.